SlideServe
Télécharger Obtenir Pro
Menu
Accueil Pro
Préférences
ApparenceLight Aide et commentaires
© SlideServe · v2026

pH Scale

rritter avatar
rritter
24 diapositives · 421 Views · Jan 04, 2020

This overview explores the pH scale, a logarithmic measure of hydrogen ion concentration ([H+]), detailing how pH values relate to acidity and alkalinity. It explains water's self-ionization process producing hydronium (H3O+) and hydroxide ions (OH-), emphasizes the significance of pH differences in solutions, and defines how to calculate [H+] and [OH-] using the pH and pOH relationships. Additionally, practical methods for safely measuring pH with indicators and meters are included, enhancing our understanding of this fundamental chemical property.

pH Scale - slide 1
01 / 24pH Scale
1 / 17

Télécharger la présentation

pH Scale
Une image / un lien ci-dessous est fourni (tel quel) pour télécharger la présentation

Politique de téléchargement : le contenu du site vous est fourni TEL QUEL pour votre information et votre usage personnel ; il ne peut être vendu, concédé sous licence ni partagé sur d’autres sites sans l’accord de son auteur.Le contenu vous est fourni TEL QUEL, pour votre information et votre usage personnel uniquement. Téléchargez la présentation en cliquant sur ce lien. Lors du téléchargement, si vous ne parvenez pas à télécharger une présentation, l’éditeur a peut-être supprimé le fichier de son serveur.Pendant le téléchargement, si vous ne parvenez pas à obtenir une présentation, le fichier a peut-être été supprimé par l’éditeur.

F I N

Plus de contenu associé

Transcription de la présentation

  1. pH Scale

  2. pH scale • Logarithmic scale expressing the H+ concentration, [H+]. • If the pH changes by a factor of 1, the [H+] changes by a factor of 10. • pH = -log[H+]

  3. - Water & Self-Ionization • H2O (l) + H2O (l) H3O+ (aq) + OH- (aq) • H3O+ is called hydronium ion • OH-is called hydroxide ion • In reality, H+ and H3O+ are used interchangeably. • H+ is called a proton or a hydrogen ion.

  4. pH of Water • Water ionizes to produce both the hydronium ion and the hydroxide ion in equal amounts. • Ionization happens to a very small extent • [H+] = [OH-] = 1 X 10-7 M • At this concentration: pH = -log[H+] = 7

  5. pH to Molarity • pH = -log[H+]. Solve for [H+]. • -pH = log[H+] • Antilog(-pH) = [H+] • Say pH = 5. Then –pH = -5. • Antilog(-5) = 10-5. • The –pH becomes the power of 10!

  6. If the pH = 4 Antilog(-pH) = [H+] Antilog(-4) = 10-4 • The [H+] = ? • The pOH = ? • The [OH-] = ? 10 Antilog(-10) = [OH-] 10-10 = [OH-]

  7. Difference in pH = 2, which means the [H+] differ by 102 or 100. The pH of 5 solution has an [H+] that is 100 X greater than that of the pH 7 solution. • If the pH changes from 5 to 7, how do the [H+] compare?

  8. Significance of pH differences • Difference in pH =5 and pH =7 • Difference is 2 units of pH • The [H+] differ by 102 or 100 • The pH of 5 solution has an [H+] that is 100 X greater than that of the pH 7 solution.

  9. pH

  10. Ion Product Constant for Water • Value of the equilibrium constant expression for the self-ionization of water. H2O (l) + H2O (l) H3O+ (aq) + OH- (aq) Keq= [H+] [OH-] [H2O] Kw= [H+] [OH-] = 10-14

  11. If the pH = 2 The [H+] = ? 1 x 10-2M

  12. If the [H+] = 1 X 10-5 M 5 • The pH = ? PROBLEM: Relative acid strength How many time stronger is an acidic solution with A pH of 2 than an acidic solution with a pH of 5? 1000x

  13. pOH • By analogy, pOH is defined as –log[OH-] • Express [OH-] in scientific notation • If [OH-] = 1.0 X 10-3 M • Then pOH = -log(10-3) = -(-3) = 3.

  14. If the [OH-] = 1 X 10-3 pOH = -log[OH-] = -log(10-3) = --3 = 3 • The pOH = ? • The pH = ? • The [H+] = ? 14 – 3 = 11 Antilog(-11) = 10-11 M

  15. If the [H+] = 1 X 10-5 M 5 • The pH = ? • The pOH = ? • The [OH-] = ? 14 – 5 = 9 Antilog(-9) = 10-9

  16. pH + pOH = 14 11 • pH = 3, pOH = • pH = 7, pOH = • pH = 10, pOH = • pH = 9, pOH = • pH = 1, pOH = 7 4 5 13

  17. Acid, Base, or Neutral? • All H2O contains some H+ and some OH- • Pure H2O – concentrations are very low. • [H+] = [OH-] = 1 X 10-7 Molar. • When [H+] = [OH-], solution is neutral • Acidic solution: H+ > OH- • Basic solution: OH- > H+

  18. 10-3 A 10-11 11 9 5 B 10-9 A 12 2 10-12 M B 10-6 M 10-8 M 8

  19. How to safely test pH • Instrumental • use a pH meter • Indicators • use a series of indicators • Reaction • Acid if reacts with metals (other than Cu, Ag, or Au)

  20. Indicator • A substance that changes color over a narrow pH range. • Use several indicators to narrow down the pH range of the substance.